Orthogonal frequency division multiplexing (OFDM) is a multi-carrier transmission scheme used in most of the existing wireless (broadband communication) standards such as LTE, WFi, WiMAX and IEEE 802.20 WRAN. The popularity of OFDM comes from the multitude of benefits it offers in terms of providing high data rate transmission and spectral efficiency, robustness against and tolerance to multipath fading, ease of implementation, simple equalization and waveform agility. OFDM signals are agile in the sense that any subcarrier can be switched on or off to fit the available transmission bandwidth, which makes it well suited for systems with dynamic spectrum access. Nonetheless, and despite all the aforementioned advantages, OFDM signals have out-of-band (OOB) power leakage as a result of high spectral sidelobes that can create severe interference to users in adjacent transmission bands and high peak-to-average power ratio (PAPR). The high spectral sidelobes are due to the use of rectangular windowing in generating OFDM signals, which have a sinc-like shape in the frequency domain that decays slowly as f−2. Both shortcomings can impact the performance of OFDM and can limit its practical applications.